Kidney and bladder stones in dogs are essentially the same, differing primarily in their location. These stones can lead to frequent urinary tract infections (UTIs), pain, and blockages, and if left untreated, can be fatal. Holistic veterinarians like Dr. Casey Damron and Dr. Marc Smith have developed protocols to help manage and understand these conditions, focusing on the dog's well-being.
Understanding Canine Kidney Stones
Stones in the urinary tract, including the kidneys (nephroliths), ureters, bladder, and urethra, are common in dogs. Urolithiasis is the medical term for these stones. Bladder stones, specifically, are the focus here, though it's important to note that stones can also occur in the kidneys.
Formation of Bladder Stones
Bladder stones form when urine becomes saturated with excess minerals like magnesium, phosphorus, calcium, and ammonia. These minerals crystallize and deposit around an organic matrix of protein. The center of the stone (nidus) can differ from the middle and outer layers, creating a compound stone.
Types of Bladder Stones
Several types of bladder stones can occur in dogs:
- Struvite Stones: Also known as magnesium ammonium phosphate (MAP) or triple phosphate, these are common, especially in female dogs, and are often associated with UTIs. Bacteria such as Staphylococcus, Proteus, Pseudomonas, Klebsiella, Corynebacterium, Enterococcus, and Mycoplasma produce urease, which breaks down urea into ammonia and carbon dioxide. High ammonia concentrations damage the bladder lining, promoting bacterial adhesion.
- Calcium Oxalate Stones: These form in acidic or neutral urine and are increasingly common.
- Urate Stones: More common in male dogs and Dalmatians, these stones form due to different protein metabolism in the liver, leading to uric acid buildup. Urate stones are radiolucent, meaning they may not show up on X-rays. Ammonium urate uroliths can also form in dogs with liver disease (Porto-Systemic Shunt - PSS).
- Calcium Phosphate Stones: No ideal diet for the prevention of calcium phosphate bladder stones has been identified, but keeping urine dilute and slightly more alkaline than normal can help.
- Silica Stones: Silica bladder stones are rare in dogs and cannot be dissolved. A diet that is high in animal protein and avoids plant-based ingredients that could be high in silica, like corn gluten, is commonly recommended to prevent silica stones.
- Compound Stones: These stones consist of a core mineral surrounded by a different mineral in a different layer, forming when the factors predisposing to one type of stone formation change.
Factors Contributing to Stone Formation
Several factors can predispose dogs to bladder stone formation:
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- Urine pH: Some stones form in acidic urine, while others form in alkaline urine.
- Bacterial Infections: Bacteria in the urine can contribute to stone formation.
- Liver Shunts (PSS): These abnormalities in blood flow to the liver can lead to the formation of ammonium urate stones.
- Medications: Some medications can increase calcium levels in urine or alter urine pH, promoting stone formation.
- Dehydration: Insufficient water intake leads to concentrated urine, increasing the risk of crystal and stone formation.
- Infrequent Urination: Stagnation of bacteria and stone-forming chemicals in the bladder increases the chance of stone formation.
- Genetics: There is a hereditary component to the formation of oxalate bladder stones.
Recognizing the Signs
Clinical signs of bladder stones can vary, but common symptoms include:
- Bloody urine
- Increased frequency of urination
- Straining to urinate
- Urinary accidents
- Vomiting
- Abdominal pain
- Lethargy
- Dehydration
In severe cases, a stone can block the urethra, leading to a life-threatening urinary obstruction.
Diagnosis
Diagnosing bladder stones involves several steps:
- Physical Examination: A veterinarian may be able to feel large stones during palpation of the abdomen.
- Urinalysis: This helps identify crystals and bacteria in the urine.
- Urine Culture and Sensitivity: This identifies any bacteria present and determines the most effective antibiotics.
- Radiography (X-rays): Many stones are radiopaque and show up on X-rays. Radiolucent stones may require contrast radiography or ultrasound for detection.
- Ultrasound: This is a precise method for diagnosing stones in the urinary bladder.
- Urolith Analysis: Analyzing the composition of a retrieved stone is crucial for determining the appropriate treatment and prevention strategies.
Treatment Options
Treatment for bladder stones varies depending on the type, size, and location of the stone, as well as the overall health of the dog.
Medical Management
- Dietary Therapy: Special prescription diets can dissolve some types of stones, such as struvite and urate stones. These diets modify urine pH and reduce mineral concentrations. Hill's Prescription Diet Derm Complete or high-quality, grain-free canned dog foods (with a little extra water added) are often good options. For struvite stones, Hill's s/d is often used.
- Antibiotics: If a UTI is present, antibiotics are necessary to eliminate the infection.
- Medications: Allopurinol can be used to minimize uric acid production in dogs with urate stones. Potassium citrate can help make the urine less acidic, preventing calcium oxalate stones. Urease inhibitors like acetohydroxamic acid may be used for persistent UTIs.
Surgical Intervention
- Cystotomy: This involves surgically removing the stones from the bladder. The laser is often used to make an incision in the bladder because of dramatically less bleeding during the surgery and dramatically less inflammation after we remove the stone and suture the bladder.
- Cystoscopy: A cystoscope is passed through the urethra into the bladder to break down the stones into small fragments that can be expelled through urine.
- Lithotripsy: This nonsurgical procedure uses laser to break down stones into tiny fragments.
Dietary Strategies for Specific Stone Types
- Struvite Stones: Therapeutic diets reduce magnesium, phosphorus, and protein while acidifying and diluting the urine.
- Calcium Oxalate Stones: Aims to create a urinary environment with minimal calcium and oxalate, and a urine pH that is not conducive to calcium oxalate formation.
- Urate Stones: A food called Hills U/D should be used. It is low in purines and has restricted protein.
- Calcium Phosphate Stones: No ideal diet for the prevention of calcium phosphate bladder stones has been identified, but keeping urine dilute and slightly more alkaline than normal can help.
- Silica Stones: A diet that is high in animal protein and avoids plant-based ingredients that could be high in silica, like corn gluten, is commonly recommended to prevent silica stones.
Prevention Strategies
Preventing recurrence of bladder stones is crucial, as dogs that develop stones once are at risk of developing them again.
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General Dietary Recommendations
- Hydration: Ensure your dog drinks plenty of water to dilute urine. Feeding wet food and adding water to dry food can help. Aim for a urine specific gravity (USG) under 1.020.
- Balanced Diet: Work with a veterinary nutritionist to formulate a complete and balanced diet appropriate for your dog's specific needs.
- Avoid Problem Foods: For calcium oxalate stones, avoid foods high in oxalate, such as spinach, sweet potatoes, organ meat, and brown rice. Instead, include low-oxalate foods like peeled apples, white rice, meats, and fish (except sardines).
- Moderate Protein: Studies suggest that moderate to higher protein levels from good-quality sources may reduce calcium oxalate stone formation.
- Adequate Calcium: Ensure your dog receives enough calcium to bind to oxalate in the digestive tract, but not so much that it increases calcium in the urine.
- Limit Sodium: Avoid adding extra salt to homemade diets, as it can increase calcium loss in urine.
- Avoid Excess Vitamins: Limit vitamin D and C supplementation, as they can increase calcium and oxalate levels, respectively. Vitamin B6 can help prevent excess oxalate production.
- Omega-3 Fatty Acids: Fish body oil supplements can help reduce bladder wall inflammation caused by calcium oxalate stones.
Monitoring and Follow-Up
- Regular Urinalysis: Monitor urine pH and check for crystals every 3-6 months.
- Radiographs: Take radiographs every 6-12 months to detect any new stones early.
Additional Considerations
- Cooling Diet: A cooling diet may help reduce inflammation.
- TCVM Herbs: Traditional Chinese Veterinary Medicine (TCVM) herbs may be recommended by a TCVM veterinarian.
- Medications: Avoid medications that can increase the risk of calcium oxalate stone development, such as prednisone and furosemide. Thiazide diuretics may be a better choice if a diuretic is necessary.
- Potassium Citrate: This medication increases citrate levels in the urine, which binds to calcium and helps create an alkaline urine.
Living with Kidney Stones: A Success Story
One pet owner shared their experience: "18 months on your diet for our calcium oxalate stone forming dog and we have no further stones and bladder is in good health. Prior to your diet his stones returned 9 months after surgery."
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